<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<script type="text/javascript">
			//global全局对象
			var str = "a123";
			var num = parseInt(str);
			alert(num);
			alert(isNaN(num));
			
			var str2="alert(num)";
			eval(str2);
		</script>
	</head>
	<body>
	</body>
</html>
